October 2019

Highly myopic eyes present a risk of retinal detachment (RD) after lens-based surgery. While the yearly incidence of retinal detachment in the general population is 6–18/100,000 (5–13/100,000 in non-traumatic phakic eyes), in the myopic population it’s at least threefold. Marlies Ullrich, MD, presented on this at the 36th Congress of the European Society of Cataract and Refractive Surgeons.
A number of studies discussed by Dr. Ullrich have investigated the incidence of RD. One study’s outcomes showed a fourfold increase in RD after cataract surgery in the general population.1 The presentation compared other studies from the literature demonstrating a cumulative incidence of 0.16–3.6% (young population) after in-the-bag IOL implantation. Still more evidence estimated a risk of 1% at 4 years after cataract surgery and a risk of 9% or higher in patients with high myopia.2 Research on the subject makes it clear that the risk of RD rises with axial lengths over 25 mm. Posterior capsule tears, zonule dehiscence, RD in the fellow eye, and male gender are also common risk factors.

RD in myopes

Investigations on the incidence of RD in myopes after lens surgery are numerous, Dr. Ullrich continued, but sometimes too different to compare. Some evidence suggests a mean 2.2% incidence of RD in myopes.3 After clear lens extraction for high myopia over –12 D (mean age 36 years), the incidence of RD was 2.0% at 4 years and 8.1% at 7 years postop.4 Elsewhere in the literature, 8% of aphakic and pseudophakic eyes between –15 and –30 D developed RD versus 1.2% of phakic fellow eyes, with the highest incidence of RD seen in eyes with myopia from –25 to –30 D.5
While the level of myopia clearly increases the risk of RD after cataract surgery, with 25 mm the axial length cutoff in many studies, age is another factor to consider. Published data shows that younger patients (under 50 years old) have a higher incidence of RD than older patients. Other research shows a risk of 10.2% in a subgroup with axial lengths of 25–29 mm in patients below 61 years old.6
The association between RD and younger patient age is of particular relevance in highly myopic RLE (refractive lens exchange) patients and also myopic cataract patients, who tend to be younger. Also, the rate of posterior capsule opacification tends to be higher in younger, RLE patients, however, the influence of YAG capsulotomy on RD is controversial. One study showed a fourfold increase in risk of retinal breaks and RD after Nd:YAG capsulotomy.7 Outcomes from different studies revealed YAG as being riskier in myopic eyes. According to further evidence every millimeter of increased axial length increases the RD risk after Nd:YAG capsulotomy by a factor of 1.5. Conversely, the outcomes of a few recent studies found no increase in RD incidence after Nd:YAG capsulotomy.

Vitreous involvement

Long eyes undergoing cataract surgery have been associated with a twofold increased risk for capsule rupture or vitreous loss, Dr. Ullrich said. Several studies showed an approximately 12–15 times higher risk for RD in eyes with capsule complications.8 Mechanical changes caused by the replacement of the thick crystalline lens by a thin IOL increases the volume of the posterior segment. The forward movement of the posterior lens capsule and the vitreous can lead to posterior vitreous detachment (PVD) development and cause dynamic traction at the posterior border of the vitreous base, with a risk of subsequent tear formation.
Hyaluronic acid distribution and concentrations can influence vitreous stability after cataract surgery, causing biomechanical changes. Also, modifications in the vitreous microenvironment can contribute to the development of retinal complications. There is evidence that anterior vitreous attachment is a prognostic sign for RD.
According to the literature presented by Dr. Ullrich, in general PVD occurs earlier in myopes compared to the emmetropic population (phakic eyes).9,10 Some degree of PVD is often detected with OCT and ultrasound after lens surgery in individuals without preoperative PVD – 71% after 3 months in nonmyopic eyes.11 Pseudophakic eyes with an axial length of ≥25 mm were shown to be more likely to have a PVD as compared to those eyes with an axial length of <25 mm, odds ratio 4.7.12 Higher percentages of new PVD after cataract surgery have been observed in younger patients and a trend towards higher occurrence of new PVD with increasing myopia was shown.13
Addressing the influence of PVD on RD after lens surgery in myopic eyes, Dr. Ullrich and her team are collecting data from 618 patients with axial lengths longer than 25 mm from 11 ophthalmology centers in six countries, as part of the Myopic Pseudophakic Retinal Detachment ESCRS Study. The study’s main outcome will be assessed after 3 years, with an extended follow-up to 5 years. The study includes funduscopy, SD-OCT, and ultrasound. Patients will be divided into two groups—complete PVD vs. partial or no PVD. The study is ongoing.
“There are number of clinical pearls to keep in mind. The presence of PVD should be assessed preoperatively, possibly with OCT. Prophylactic treatment with laser is controversial, however, it could be considered for example in an RD fellow eye with lattice. RLE in myopes, which requires an extensive informed consent procedure, might best be applied in patients over 55 years of age with PVD,” Dr. Ullrich said.